2019_programme: METHOD FOR LOW FREQUENCY CALIBRATION IN CONFINED MEASUREMENT TANK

• Session: 02. Underwater acoustic calibration, testing, facilities and standards
  Organiser(s): Robinson Stephen, Humphrey Victor, Linné Markus, Évora Victor
• Lecture: METHOD FOR LOW FREQUENCY CALIBRATION IN CONFINED MEASUREMENT TANK
  Paper ID: 813
  Author(s): Abrahamsson Per
  Presenter: Abrahamsson Per
  Presentation type: oral
  Abstract: To calibrate hydrophones and transducers is essential for measurements in the underwater domain. Due to the large wave-lengths for low frequency sound, below 4 kHz, problems occur when these transducers or hydrophones are measured in a confined test tank with limited space – mainly due to the multi-path that occurs in the tank. One way to eliminate these problems is to do the measurements in free-water where the risk of multi-path is eliminated. But a free-water measurement has other drawbacks that can be eliminated in controlled test environments such as a tank. In this paper a previously reported method for eliminating the impact of the tank is used, together with some new adaptations. By viewing the tank conditions as a transfer function between the transducer and the hydrophone, high quality measurements can be done in the controlled environment of a tank. This means that if the transfer function can be properly estimated, then the impact of the tank can be almost eliminated. To verify the method, both free-water and tank measurements has been performed. To be able to estimate suitable positions for the transmitter and hydrophone, a numerical wave propagation model was used. The result from the model was applied together with a series of measurements to estimate the method’s robustness against positioning errors.
    Download the full paper
• Corresponding author: Mr Abrahamsson Per
  Affiliation: Saab Dynamics
  Country: Sweden
  e-mail: